The Whisky Production Process: Part 2 - Mashing

The whisky production process is made up of 5 distinct steps and they are as follows:

- Malting

- Mashing

- Fermentation

- Distillation

- Maturation

Having delved into the malting aspect of the process last week, we continue our journey this week with the next step: Mashing.

At the end of the malting process, the malted barley is ground down in a mill and is transformed into a product known as grist. The grist, which resembles porridge oats in appearance, is then transferred into a vessel known as a mash tun for the mashing process to commence.

The mash tun at Bowmore

The mash tun is a large circular vessel which is traditionally made from stainless steel, cast iron or copper (although it tends to be clad in wood for aesthetic purposes) and each distillery in Scotland has a different style and size of mash tun in accordance with their requirements.

While the majority of the modern distilleries in Scotland are equipped with a stainless steel mash tun, some distilleries still utilise the old copper or cast iron mash tuns from years ago and it isn't unusual to see distilleries replace their copper mash tuns with stainless steel and then affix the old copper canopy on top.

These mash tuns either have a canopy on top or be left open so that the process is visible to all and some distilleries even utilise open top mash tuns with rakes which are made of cast iron and date back to the 1800s.

The mash tun at Bruichladdich dates back to 1881 (the year of the distillery's inception) and is both the shell and the rakes are made from cast iron. The rakes were replaced in 2013/2014 and the parts were custom made for the distillery.

Once the grist is added to the mash tun, it is then subjected to three different charges of water which are heated to different temperatures. The first charge is heated to 63 degrees Celsius and this temperature is high enough to begin the process of converting the starch in the grist into maltose (or malt sugar) by using amylase beta.

After some time, the sugary liquid, which is known as wort, is drained from the mash tun and stored in a tank known as an underback until it has cooled. The process is then repeated twice more and water which is heated to 74 degrees Celsius and 85 degrees Celsius respectively are then added to the mash tun so that it can allow the amylase alpha to convert the maltose into two different glucose molecules.

The underback at Laphroaig, like their mash tuns, are made from stainless steel.

During each stage of the mashing process, the rakes continuously move the mash around to minimise clumping while also ensuring that the maximum amount of wort is collected for the next stage, which is fermentation.

At the end of the mashing process, the residual product within the mash tun, which is known as draff, is collected and processed into pellets and then sold as cattle feed. The reason for doing so would be due to the nutritious nature of the draff and it being beneficial for cattle while also ensuring that there's minimal waste generated from mashing.

Some of the draff is also used as a source of fuel for biomass boilers at certain distilleries and this allows them to generate a fairly significant portion of their energy requirements while reducing their dependence on fossil fuels and the national grid. The use of biomass boilers also ensures that theres a minimal impact on the environment due to the emission of greenhouse gases.

In recent years, there has been a noticeable push towards sustainable production processes within the whisky industry and it has been said that the use of biomass boilers and other sustainable practices will shape the future of how whisky is made.